When a permanent vacancy in the office of coroner occurs and the position is an appointed one, the county board shall fill the vacancy within 60 days from the time the vacancy occurs. If the sheriff of the county is selected to perform the duties of the coroner and the sheriff agrees to serve in that capacity, the sheriff may be compensated for those duties. This compensation shall be in addition to all other compensation received as sheriff. Any sheriff who is serving as coroner before the effective date of this amendatory Act of 1991 must be reappointed in order to continue to serve as coroner and to receive additional compensation under this Section.